Clear stale context window on session reset

src/auto-reply/reply/agent-runner.runreplyagent.e2e.test.ts

@@ -1266,6 +1266,7 @@ describe("runReplyAgent typing (heartbeat)", () => {
         sessionFile: transcriptPath,
         modelProvider: "qwencode",
         model: "qwen3.5-plus-2026-02-15",
+        contextTokens: 123456,
         systemPromptReport: {
           source: "run",
           generatedAt: Date.now(),
@@ -1316,11 +1317,13 @@ describe("runReplyAgent typing (heartbeat)", () => {
 
       expect(sessionStore.main.modelProvider).toBeUndefined();
       expect(sessionStore.main.model).toBeUndefined();
+      expect(sessionStore.main.contextTokens).toBeUndefined();
       expect(sessionStore.main.systemPromptReport).toBeUndefined();
 
       const persisted = JSON.parse(await fs.readFile(storePath, "utf-8"));
       expect(persisted.main.modelProvider).toBeUndefined();
       expect(persisted.main.model).toBeUndefined();
+      expect(persisted.main.contextTokens).toBeUndefined();
       expect(persisted.main.systemPromptReport).toBeUndefined();
     });
   });

src/auto-reply/reply/agent-runner.ts

@@ -280,6 +280,7 @@ export async function runReplyAgent(params: {
       abortedLastRun: false,
       modelProvider: undefined,
       model: undefined,
+      contextTokens: undefined,
       systemPromptReport: undefined,
       fallbackNoticeSelectedModel: undefined,
       fallbackNoticeActiveModel: undefined,

src/gateway/server-methods/sessions.ts

@@ -136,6 +136,7 @@ function stripRuntimeModelState(entry?: SessionEntry): SessionEntry | undefined
     ...entry,
     model: undefined,
     modelProvider: undefined,
+    contextTokens: undefined,
     systemPromptReport: undefined,
   };
 }
@@ -519,13 +520,10 @@ export const sessionsHandlers: GatewayRequestHandlers = {
     const next = await updateSessionStore(storePath, (store) => {
       const { primaryKey } = migrateAndPruneSessionStoreKey({ cfg, key, store });
       const entry = store[primaryKey];
+      const resetEntry = stripRuntimeModelState(entry);
       const parsed = parseAgentSessionKey(primaryKey);
       const sessionAgentId = normalizeAgentId(parsed?.agentId ?? resolveDefaultAgentId(cfg));
-      const resolvedModel = resolveSessionModelRef(
-        cfg,
-        stripRuntimeModelState(entry),
-        sessionAgentId,
-      );
+      const resolvedModel = resolveSessionModelRef(cfg, resetEntry, sessionAgentId);
       oldSessionId = entry?.sessionId;
       oldSessionFile = entry?.sessionFile;
       const now = Date.now();
@@ -540,7 +538,7 @@ export const sessionsHandlers: GatewayRequestHandlers = {
         responseUsage: entry?.responseUsage,
         model: resolvedModel.model,
         modelProvider: resolvedModel.provider,
-        contextTokens: entry?.contextTokens,
+        contextTokens: resetEntry?.contextTokens,
         sendPolicy: entry?.sendPolicy,
         label: entry?.label,
         origin: snapshotSessionOrigin(entry),

src/gateway/server.sessions.gateway-server-sessions-a.test.ts

@@ -606,6 +606,7 @@ describe("gateway server sessions", () => {
           updatedAt: Date.now(),
           modelProvider: "qwencode",
           model: "qwen3.5-plus-2026-02-15",
+          contextTokens: 123456,
         },
       },
     });
@@ -614,7 +615,7 @@ describe("gateway server sessions", () => {
     const reset = await rpcReq<{
       ok: true;
       key: string;
-      entry: { sessionId: string; modelProvider?: string; model?: string };
+      entry: { sessionId: string; modelProvider?: string; model?: string; contextTokens?: number };
     }>(ws, "sessions.reset", { key: "main" });
 
     expect(reset.ok).toBe(true);
@@ -622,6 +623,7 @@ describe("gateway server sessions", () => {
     expect(reset.payload?.entry.sessionId).not.toBe("sess-stale-model");
     expect(reset.payload?.entry.modelProvider).toBe("openai");
     expect(reset.payload?.entry.model).toBe("gpt-test-a");
+    expect(reset.payload?.entry.contextTokens).toBeUndefined();
 
     ws.close();
   });